The procedure of Garrison and Freedman will be used to induce bacterial endocarditis in rabbits. This involves placement of a plastic catheter in the venous circulation for several days, followed by an intravenous injection of bacteria, and usually results in tricuspid valve endocarditis. This model will be used to study problems encountered in narcotic addicts with Pseudomonas endocarditis. The dynamics of infection refractory to antibiotic therapy (carbenicillin, gentamicin, polymyxins) will be studied at the cellular level. The model will also be studied using enterococci, mycoplasmas, and other organisms. Newer forms of treatment of enterococcal endocarditis will be evaluated. The nitroblue tetrazolium test and various immunological tests will be studied in this system, and any immunological consequences of the disease will receive special attention as the study progresses.